1. Field of the Invention
The present invention relates to a molding and transporting apparatus, and a method therefor, for using molding sand to form a mold and for transporting the mold to a pouring step.
2. Related Arts
A well-known molding machine for producing a mold for casting blows sand into and fills a molding space between two dies, an upper and a lower or a front and a rear, in which a pattern having a desired shape is formed, while a compression plate tamps and compacts the sand. The completed casting mold is then relocated for a pouring step, and molten metal is poured into the cavity formed in the mold.
An example conventional molding machine is a horizontal molding machine wherein upper and lower dies, in the horizontal faces whereof complimentary patterns are formed, are supported by upper and lower shutterings arranged to provide an intervening gap, and whereby upper and lower molds are formed, by the main bodies of the upper and lower dies, that subsequently are aligned vertically and laminated.
Another type of conventional molding machine forms molds using shuttering supported front and rear dies wherefor complimentary recessed portions, i.e., comprising metal pouring patterns, are formed in the vertical faces, and ejects the obtained molds sequentially onto a flat plane where adjacent molds are closely aligned to define pouring cavities having the shape of a product.
The horizontal molding machine is superior in that when a horizontal mold requiring a core is manufactured, the core can be stably positioned and supported in the mold. Thus, with this machine, a simple core setting operation and a satisfactory precision product can be expected.
Since the horizontal molding machine is vertically divided by a match plate, which includes a model pattern portion, inserted into the middle of the molding space, the air-jet propulsion of molding sand must be performed from both sides of the main bodies of the dies. Therefore, because of the weight of sand, a sand tank is located above the molding section, and supply shooters, located at both sides of the main bodies of the dies, blow the sand horizontally. With this configuration, however, the size of the machine tends to be increased, as is the cost of manufacturing the shooter section, and the time required for the sand propulsion cycle is extended.
Furthermore, for the horizontal molding machine, the pattern is transferred by using the model that is formed in the match plate located in the middle of the molding space. In this case, when sand at both sides is compacted by the compression plates, and displacement of the sand is restrained merely by the unmoving flat face of the plate against which the mold is formed, an inferior mold is produced.
However, when a vertical molding machine is designed so that pattern plates bearing model patterns are located on the pressing face sides of the front and rear dies corresponding to the side faces of a mold, and for molding, the pattern plates are used to apply compression, sand closely attached to the model pattern is displaced and a satisfactory mold formation can be obtained.
According to this vertical molding machine, the pattern plates are arranged on both sides, and a pouring port can also be formed by using the pattern faces. Therefore, with a simple structure whereby sand from a sand tank located above is blown vertically, sand filling can be completed within a short period of time.
On the other hand, for the vertical molding machine, the sand mold is transported to the pouring step with the two vertically split molds closely aligned. Therefore, for a product for which a core is required, supporting the core in the mold becomes a problem, and formation of a mold may be difficult. Further, the core insertion operation and product precision may be adversely affected.
<Prior Arts>
As an conventional example, a flaskless molding machine has been proposed in Japanese Patent Laid-Open Publication No. Sho 59-220249. According to the flaskless molding machine shown in FIGS. 1 and 2 in this publication, right and left or upper and lower shutterings, which are supported by a guide shaft that rotates at a rotary shaft 4, are rotated between a molding station and a shuttering removal station, and a core insertion operation can be easily performed by rotating inferior shuttering receiving frames 21 and 22, which are attached to a rotation column 19, and a match plate receiving frame 23.
First, sand is vertically and linearly blown into the molding space and compacted. Thereafter, at the rotary shaft 4, the shutterings are rotated 90 degrees and moved to the shuttering removal station and a core is inserted. Thereafter, a shuttering removal cylinder synchronously descends to remove the upper and lower molds from the shutterings and to transport the obtained molds. Thus, the flaskless molding machine disclosed in this publication has the same advantages as are provided by both the conventional vertical molding machine and the horizontal molding machine.
However, for a flaskless molding machine, the installation of a molding station is required that covers the rotational range of the guide shaft, the diameter of which includes an opening margin for the shutters, and a shuttering removal and core insertion station is required that moves vertically, at a location within the rotational range wherein the guide shaft is arranged horizontally, and that performs the shuttering removal and the core insertion. As a result, the actual size of this molding machine is greatly increased, and not only is a large amount of vertical and horizontal installation space required, but also, manufacturing costs are increased.
Further, since the shutterings are slidably supported by the guide shaft, which pivots at the rotary shaft 4, a larger load is imposed on the guide shaft or the bearing of the rotary shaft 4. And therefore, the replacement cycle for these parts is shortened, increasing both maintenance costs and the power load.
Furthermore, the molding machine disclosed in Japanese Patent Laid-Open Publication No. Sho 59-220249 has the single function of serving as a horizontal molding machine wherein a match plate 11 is located in the middle of the molding space and whereby molds are merely vertically laminated and transported to the pouring step. Thus, since the molding machine is designed so that molding sand is compacted from both sides by flat plates, and therefore a portion of sand to which a smaller pressing force is applied is pressed against the model pattern face, a definite problem exists in that an inferior mold formation process is performed and the product precision is deteriorated.